1. Field of the Invention
This invention relates to microwave oven structures and in particular to means for providing microwave energy from the generating means to the oven cavity.
2. Description of the Background Art
In the conventional microwave oven, a magnetron or the like is provided for generating microwave energy for use in heating objects disposed within an associated oven cavity. A waveguide is provided for conducting the microwave energy from the generating means through an inlet opening in the wall of the oven cavity.
In one form of microwave oven, the waveguide is tuned. One example of such a tuned waveguide is illustrated in U.S. Pat. No. 3,867,605 of Allan Yee. As shown therein, the tuner comprises a waveguide fastener secured to the bottom wall of the waveguide as by conventional rivet means.
It is further conventional to provide a stirrer within the oven cavity for distributing the microwave energy delivered through an inlet opening. The stirrer conventionally is arranged to rotate adjacent the inlet opening and in the above-identified Yee patent, a motor driven stirrer is provided, including a center disc having attached thereto a stirrer ring with projecting portions so as to define a capacitor with eight rotating antennae.
Peter H. Smith shows, in U.S. Pat. No. 3,300,615, an electronic oven having a baffle plate within the oven adjacent the inlet opening functioning to spread the microwave energy substantially evenly around the periphery of the interior of the oven.
In U.S. Pat. No. 3,748,423, Duane B. Haagensen shows a microwave oven having a plate provided to confine the microwave power to a more restricted opening to effect a more complete diversion of energy. The deflector includes a shaft that permits a swinging movement of the plate. Means are provided connected to the door of the device to cause the plate to be advanced into the waveguide when the door is opened and to be withdrawn therefrom when the door is closed.
Stewart C. Johnson shows, in U.S. Pat. No. 3,211,880, a microwave oven wherein a deflector is provided at an angle to the inlet opening.
Franklin J. Smith shows, in U.S. Pat. No. 3,446,929, a microwave apparatus wherein the waveguide is provided with a plurality of slots to provide for distributed injection of energy from a generator into the heating space. A baffle is mounted near the central portion of the tunnel for coupling the microwave energy into the tunnel.
Werner Golombek et al show a waveguide structure in U.S. Pat. No. 3,522,550, wherein a tuning stub is provided which, by suitable adjustment, moves the mean operating point of the system from the center of the generator diagram to the region of high efficiency in high output power.
In U.S. Pat. No. 3,965,325, Kazumi Hirai shows a microwave oven utilizing a microwave energy reflector which directs the microwave energy onto a fan for conducting cooling air through the oven and which apparently directs the microwaves in a disperse manner into the oven chamber.
Mahlon W. Slocum et al show, in U.S. Pat. No. 4,035,749, a microwave tuning screw assembly mounted in the opening of the oven cavity or waveguide to provide positive shorting at an inner wall of the cavity or waveguide.